This invention pertains to the art of filters and more particularly to liquid filters.
The invention is particularly applicable to a permanent, reuseable and foldable filter for automatic coffee brewing apparatus and will be described with particular reference thereto. However, it will be appreciated by those skilled in the art that the concepts of the invention have broader applications and may be utilized in other environments and apparatus for filtering other liquids and liquid-like substances.
Drip type coffee makers have been used in commercial establishments for many years. In recent years, however, drip type coffee makers for home use have been introduced into the marketplace and have received wide customer recognition. Basically, drip type coffee makers utilize prepackaged or a measured amount of dry coffee granules placed in a filter basket which communicates with a source of hot water. A predetermined amount of hot water is introduced into the filter basket to intermix with the coffee granules and be converted into coffee. This coffee then flows from the bottom area of the filter basket into a conventional serving container or carafe. Typical of such home type drip coffee makers are those manufactured by North American Systems, Inc. of Cleveland, Ohio under the trademark MR. COFFEE.
In conjunction with drip coffee makers, a filter is inserted into the filter basket which, in turn, receives the coffee granules. This filter acts to prevent the granules or grounds themselves from undesirably passing through the filter basket into the serving container or carafe. Heretofore, the vast majority of these filters have been constructed from a paper-like material. As such, they are only useable once and are then discarded along with the coffee grounds when brewing has been completed. The paper filters are packaged in quantity and typically have a generally cup-shaped configuration with a flat bottom wall area and a pleated side wall. Because of this shape, the quantity packaging requires added shelf storage space. Moreover, the pleated side wall can allow passage of hot water between the filter basket side wall and filter without contacting the coffee granules to thereby dilute the coffee being brewed.
It has been desired to develop and provide a permanent type, reuseable filter for use in conjunction with drip type coffee making apparatus. While there have been some prior efforts in this regard, such efforts have resulted in filter structures having a relatively rigid frame or skeleton for supporting a filter material such as a woven polyester monofilament. This frame or skeleton itself has a generally cup-shaped configuration so as to be received in a cup-shaped filter basket. While this prior permanent type, reuseable coffee filter has found commercial success, the overall design does have certain undesirable characteristics.
For example, the rigid skeleton which preforms the filter does not allow substantial variation in the type of filter basket with which it is used so that a wide variety of types and styles are necessarily required to accommodate the coffee brewing apparatus of different manufacturers. Further, the rigid cup-shaped skeleton or frame requires additional materials which increases manufacturing costs and resultant resale costs to the consumer. Still further, since these filters are supplied in a preformed cup-shaped configuration, they necessarily require packaging in somewhat larger boxes or the like. As with the paper filters, this reduces the number of such filters which may be placed on typical store shelves and thereby necessitates more frequent restocking.
Accordingly, it has been found desirable to develop a permanent type, reuseable filter construction which would overcome the aforementioned problems and others which have been encountered with prior filter designs. The present invention provides a new filter design and construction which is easy to manufacture, inexpensive to manufacture, reuseable for an extended period of time, selectively foldable between a generally flat storage condition and a use condition with associated support structure and readily adapted for use in a number of different environments for filtering different liquids.